1. Field of the Invention
The present invention is directed to a reflection type semiconductor display device of a direct viewing type, and more particularly, to a reflection type liquid crystal display device (liquid crystal panel). The present invention also relates to a semiconductor device with a reflection type liquid crystal display device mounted thereon.
A semiconductor device as referred to in the present invention may be, for example, used information processing equipment such as a notebook-sized personal computer, a lap top type personal computer, an electronic notebook, or a mobile computer, a video camera, a digital still camera, a car navigation system, or a cellular telephone.
2. Description of the Related Art
Recently, an intensive study and development have been carried out with regard to manufacturing technology of liquid crystal panels to make it possible to provide liquid crystal panels at a relatively low cost. Further, as the information society where Internet, electronic mail, and the like are utilized has been developed, notebook-sized personal computers (hereinafter abbreviated as notebook-sized PCs) have rapidly become more popular.
With regard to digital still cameras and video cameras, as they have been allowed to have liquid crystal panels mounted thereon such that images taken can be viewed on the spot, they have become widely accepted by consumers.
Liquid crystal panels fall into two types, transmission type ones and reflection type ones. In a transmission type liquid crystal panel, illumination light is transmitted through the liquid crystal panel from a back light provided at the back so that the user can visually confirm the display. On the other hand, a reflection type liquid crystal panel does not need a back light, and the display can be seen through reflection of external light on the liquid crystal panel. Since a back light consumes about 90% of power consumption of the so transmission type liquid crystal panel, power consumption of a transmission type liquid crystal panel is large. On the other hand, though the display quality level of a reflection type liquid crystal panel is inferior to that of a transmission type liquid crystal panel, power consumption of a reflection type liquid crystal panel is smaller than that of a transmission type liquid crystal panel, and thus, a reflection type liquid crystal panel is advantageous when used in a notebook-sized PC or a mobile PC.
One reason for the inferiority of the display quality level of a reflection type liquid crystal panel to that of a transmission type liquid crystal panel could be the insufficient amount of light when it is used indoors.
These days, in order to solve the problem of the insufficient amount of light, a technique to provide a reflection type liquid crystal panel with a front light is adopted to supplement the insufficient amount of light when it is used indoors. However, in this case, since a fluorescent lamp similar to that used as a back light of a transmission type liquid crystal panel is used as the front light, leading to larger power consumption, the advantage of a reflection type liquid crystal panel cannot be obtained.
Accordingly, the present invention has been made in view of the above problem, and an object of the invention is to provide a reflection type semiconductor display device having a high display quality level without insufficiency in the amount of light even when it is used indoors.
In order to solve the above problem, according to the present invention, light other than incident light on a liquid crystal panel is utilized as an auxiliary light source for a reflection type semiconductor display device.
FIG. 1 shows a schematic structural view of a reflection type semiconductor display device using a reflection type liquid crystal panel according to the present invention. Reference numerals 101, 102, and 103 denote a main body, a reflection type liquid crystal panel, and an optical fiber array, respectively. The optical fiber array 103 includes a plurality of optical fiber cables 104. Each of the optical fiber cables 104 is a bundle of a plurality of optical fibers, examples thereof being shown in FIGS. 2A and 2B. The optical fiber array is used as means for taking in external light.
In FIGS. 2A and 2B, reference numeral 201 denotes an optical fiber, an enlargement thereof being shown at the lower portion in FIGS. 2A and 2B. The optical fiber 201 has a core and a clad. The index of refraction of the core is larger than that of the clad, and light travels as it repeats total internal reflections at the interface between the core and the clad. A coating 202 is formed of a resin or the like. A reinforcing material 203 is formed of a resin or the like.
It is to be noted that, in the optical fiber cable 104 shown in FIG. 2A, a bundle of tightly packed optical fibers is covered with the coating 202. Further, in the optical fiber cable 104 shown in FIG. 2B, the reinforcing material 203 fills the space among the optical fibers to improve the strength.
Next, reference is made to FIG. 3. FIG. 3 shows a sectional view of a reflection type liquid crystal panel according to the present invention. Reference numeral 301 denotes a substrate. Reference numerals 302 and 303 denote driver TFTs (thin film transistors). Reference numerals 304,305,306, and 307 denote a pixel TFT, a reflection electrode, liquid crystal, and a counter substrate, respectively. It is to be noted that the pixel TFT can be made of amorphous semiconductor film or polycrystalline semiconductor film. Also, it is to be noted that a transparent electrode (not shown) is provided under the counter substrate.
The optical fiber cables 104 are positioned such that light taken in from one end of each of the optical fiber cables 104 is emitted from the other end thereof to the counter substrate. Consequently, incident light entered into the optical fiber cables travels through the optical fibers, enters the counter substrate 307, travels through the counter substrate 307, and then enters the liquid crystal. It is to be noted that the upper surface of the counter substrate 307 is appropriately processed to allow incident light on the liquid crystal by eliminating the requirement for the total internal reflections of light traveling through the substrate at the interface. The processing condition can be most suitably set through simulation or the like. In FIG. 3, the upper surface of the counter substrate 307 is formed with patterns, but the present invention is not limited thereto.
Alternatively, as shown in FIG. 4, the panel may be structured to use a counter substrate used in a general reflection type liquid crystal panel and a light guide plate 408. Reference numeral 401 denotes a substrate. Reference numerals 402 and 403 denote driver TFTs. Reference numerals 404, 405, 406, and 407 denote a pixel TFT, a reflection electrode, liquid crystal, and a counter substrate, respectively. In this case, the upper surface of the light guide plate 408 is processed so as to eliminate the requirement for the total internal reflections of incident light traveling through the light guide plate 408 at the interface.
It is to be noted that any suitable means may be used to allow incident light taken in by the optical fiber cables 104 to travel through the counter substrate or the light guide plate into the liquid crystal.
The present invention will be described in view of the structure.
According to the present invention, there is provided a reflection type semiconductor display device in which light emitted from one end of an optical fiber enters said reflection type semiconductor display device, wherein the light is external light taken in from the other end of the optical fiber.
Further, according to the present invention, there is provided a reflection type semiconductor display device in which light emitted from one end of an optical fiber enters a counter substrate of said reflection type semiconductor display device, wherein the light is external light taken in from the other end of the optical fiber.
Still further, according to the present invention, there is provided a reflection type semiconductor display device in which light emitted from one end of an optical fiber enters a light guide plate provided so as to oppose said reflection type semiconductor display device, wherein the light is external light taken in from the other end of the optical fiber.
Preferably, the reflection type semiconductor display device in the foregoing structures further comprises a microlens.
Preferably, the reflection type semiconductor display device in the foregoing structures further comprises a front light.
Preferably, the above-described front light comprises a LED.